1. Field of the Invention
This invention relates generally to pressure sensing circuits, and more particularly to a monolithically integratable circuit for generating a linear voltage proportional to 1/C.sub.P where C.sub.P is the capacitance of a pressure sensitive capacitive transducer.
2. Description of the Prior Art
Pressure sensors which utilize building-block integrated circuits to detect the frequency of two oscillators are known. The first oscillator generates a signal having a frequency which is proportional to the capacitance of a reference capacitor. To determine pressure, the signal is compared with the output of a second oscillator having a frequency which is proportional to the varying capacitance of a capacitive transducer. However, because this circuit is configured in an open loop configuration, it suffers from a substantial amount of inherent drift thus reducing its accuracy. Furthermore, due to the necessity of using a large number of components, the known arrangement is complicated, expensive, and does not lend itself to state-of-the-art thick-film technology.